#include <stdio.h>
int main()
{
	int a = 0;
	printf("please input a numder:");
	scanf("%d", &a);
	switch (a)
	{
		case 1:
			int b = 0;
			printf("please input a numder:");
			scanf("%d", &b);
			switch (b)
			{
				case 1:
					printf("11");
					break;
				case 2:
					printf("12");
					break;
			}
			break;
		case 2:
			int c = 0;
			printf("please input a numder:");
			scanf("%d", &c);
			switch (c)
			{
				case 1:
					printf("21");
					break;
				case 2:
					printf("22");
					break;
			}
			break;
		case 3:
			int d = 0;
			printf("please input a numder:");
			scanf("%d", &d);
			switch (d)
			{
				case 1:
					printf("31");
					break;
				case 2:
					printf("32");
					break;
			}
			break;
	}
}
